U.S. Pat. No. 4,028,383 describes a class of indolopyrone carboxylic acids and their esters which are useful antiallergic compounds. U.S. Pat. No. 4,110,464 claims a method for preventing allergic and asthmatic reactions in mammals upon administration of a compound chosen from among certain indolopyrone carboxylic acids and their esters.
The present invention describes a class of indolopyrone tetrazoles and carboxamidotetrazoles which possess enhanced activity when compared to the corresponding acids, for the prevention of allergic and asthmatic reactions in mammals.